This invention relates to apparatus and methods for forming bodies. More particularly, the invention concerns apparatus and methods for forming bodies by deposition of a weld material.
The formation of components for aerospace engines can be carried out by any of several techniques of deposition of a weld material. These techniques involve the striking of an arc between two electrodes, the first electrode being held in a welding head to which is fed a supply of a weld material, the supply being in the form of a wire of the material wound upon a reel. The second electrode is in the form of a substrate or foundation upon which the weld material is to be deposited to form the component. The foundation may be in the form of a metal plate. A supply of an inert gas is fed to the welding head during its operation.
When the welding head and the foundation are connected to a supply of electricity, an arc is formed in the inert gas which melts the metal wire and the substrate. The metal is then deposited onto the foundation in a controlled manner. The welding head is mounted on a robotic arm and the plate is mounted on a movable turntable. By controlling the movement of the arm and the turntable, the metal can be deposited on the plate in order to form components of any desired shape.
One such method of forming components involves providing the welding head with a permanent electrode and also providing a separate metal wire to the welding head. This method is generally known in the art of tungsten inert gas welding which is generally shortened to TIG welding. The use of the word tungsten is intended as a synecdoche, and it will be appreciated by those skilled in the art that other suitable materials could be used as the electrode.
Another such method involves the use of a sacrificial electrode in the welding head. With this arrangement, the metal wire which provides the weld material also constitutes the electrode and is fed through the welding head. This method is generally known in the art as metal inert gas welding, which is generally shortened to MIG welding.
A problem with such techniques is that stresses can build up in the component, so that the component distorts when it is released from the plate.
According to one aspect of this invention there is provided a method of forming a body by deposition of a weld material, the method comprising providing a welding head and a support member upon which the body is to be formed, supplying a weld material to be deposited on the support member and connecting the support member and the welding head to a supply of electricity to form an arc between the welding head and the support member or the body to melt the material, wherein a raised member is provided on the support member, the support member and the welding head are manipulated relative to each other to deposit the material on the raised member and form said body thereon, wherein the raised member is configured to inhibit the conduction of heat from the body during formation of the body.
The method may further include a step of manipulating the welding head and the support member relative to each other to deposit a weld material on the support member to form the raised member before the step of forming the body on the raised member.
According to another aspect of this invention there is provided apparatus for forming a body by deposition of a weld material, the apparatus comprising a welding head, a support member on which the body is to be formed, and means for supplying a weld material, wherein the support member includes a raised member upon which the body can be formed.
The support member may be supported on support means which may comprise a turntable movable to a desired position.
According to another aspect of this invention, there is provided a support arrangement for use in forming a body by deposition of a weld material comprising a support member, and a raised member on the support member, on which the body can be formed.
Preferably, the raised member is configured to inhibit the conduction of heat from the body during formation of the body. The raised member may comprise a first section upon which the body is formed, and a second section extending from the first section to the support member, the second section being of a narrower cross-section than the first section. Preferably, the first section tapers inwardly to the second section. The second section may taper outwardly to the support member.
The weld material may be a titanium alloy, for example titanium 6/4, which includes 6% aluminium and 4% vanadium, or the weld material may be any other suitable alloy.
In one embodiment, the raised member is in the form of a wall which may extend around the foundation and which is preferably annular.